configs/kontron_bl_imx8mm: U-Boot needs util-linux

Fixes:

/usr/bin/ld: cannot find -lgnutls
/usr/bin/ld: cannot find -luuid
collect2: error: ld returned 1 exit status

when building U-Boot.

Fixes:

  https://gitlab.com/buildroot.org/buildroot/-/jobs/3301821264



Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>